This was my favorite growing up. Mostly because of the marshmallows.
3-5 sweet potatoes (depending on size)
3/4 c brown sugar
2 t cinnamon
1 t nutmeg
1/2 t cloves
1 bag mini marshmallows
Poke holes in the sweet potatoes with a fork, then place on a foil wrapped jelly roll pan. Bake at 350 for about an hour - until "meat" is starting to soften. Let cool. Peel sweet potatoes, then slice about 1-1.5 inch thick. Place in a greased 9x13 pan. In a small bowl, mix sugar, cinnamon, nutmeg and cloves (all amounts are approx). Sprinkle 1/3 of mixture over sweet potatoes. Peel and thinly slice apples and layer on top of the sweet potatoes. Cover with remaining sugar mixture. Set aside until about 25 minutes before dinnertime. Bake at 350 for about 20 minutes, or until apples soften. Remove from oven and add marshmallows on top. Put back in the oven for a couple minutes, watching carefully, until marshmallows have started to brown. Serve.
PS- some people like to add walnuts on top of the apples and under the remaining sugar mixture.